Some communications systems consist of a host (such as a laptop computer) with an interface for a Universal Serial Bus (USB) or radio-linked device. If the host device is assumed to have a 0 dB loss plan in its default state, then the relevant clauses of this standard are directly applicable to the USB or radiolinked device. If the host system provides gain or loss in the send path, receive path, or both, then the relevant clauses of this standard apply to the composite system